Differences between Chromatium Minutisslnum and Rhodospirillum Rubrum in Phytohormonal Composition

Abstract

Plant hormones belong to compounds widespread in nature. Their structure and functions have been well studied not only in higher plants but also in non-phototrophic microorganisms entering into various kinds of interactions with plants. However, a rather large group of phototrophs, namely the phototrophic purple bacteria, have fallen out of the field of vision of phytohormone researchers and these substances have not been studied in these bacteria up to the present (1). The phototrophic bacteria in physiological and morphological properties represent a heterogenous group of microoganisms. In their phenotypical features they are divided into several large families consisting of numerous genera. But phylogenetic analysis of 16S rRNA nucleotide sequences permitted to divide phototrophic bacteria into just a few classes, namely the α -, β- and γ -subdivisions; some representatives of purple bacteria proved to be in closer relationship to nonphototrophic microorganisms than between themselves (2). As mentioned above some non-phototrophic bacteria have the ability to synthesize phytohormones. Cytokinins or auxins play a key role under parasitic or symbiotic interections of non- phototrophic bacteria with plants. Purple bacteria are free-living microorganisms. But sometimes these bacteria can be found in the rhizosphere of such aqueous cultures as rice or Azolla but their importance for plants has not been clearly determined. Thus, the question arose of the presence and content of phytohormones as well as of their function in these bacteria. Besides this, the formation and selection of structures concerning photosynthesis and its regulation, ocurring namely in these bacteria, is the result both of similarity and the difference of these features between the bacteria themselves as well as between the bacteria and plants. Phytohormones apparently are not the exeption. Thus, purple bacteria can be an interesting object not only in studies of structure and function of phytohormones but of their evolution.